Hybrid SSF/SHF Processing of SO2 Pretreated Wheat Straw-Tuning Co-fermentation by Yeast Inoculum Size and Hydrolysis Time.

Wheat straw is one of the main agricultural residues of interest for bioethanol production. This work examines conversion of steam-pretreated wheat straw (using SO2 as a catalyst) in a hybrid process consisting of a short enzymatic prehydrolysis step and a subsequent simultaneous saccharification and fermentation (SSF) step with a xylose-fermenting strain of Saccharomyces cerevisiae. A successful process requires a balanced design of reaction time and temperature in the prehydrolysis step and yeast inoculum size and temperature in the SSF step. The pretreated material obtained after steam pretreatment at 210 °C for 5 min using 2.5 % SO2 (based on moisture content) showed a very good enzymatic digestibility at 45 °C but clearly lower at 30 °C. Furthermore, the pretreatment liquid was found to be rather inhibitory to the yeast, partly due to a furfural content of more than 3 g/L. The effect of varying the yeast inoculum size in this medium was assessed, and at a yeast inoculum size of 4 g/L, a complete conversion of glucose and a 90 % conversion of xylose were obtained within 50 h. An ethanol yield (based on the glucan and xylan in the pretreated material) of 0.39 g/g was achieved for a process with this yeast inoculum size in a hybrid process (10 % water-insoluble solid (WIS)) with 4 h prehydrolysis time and a total process time of 96 h. The obtained xylose conversion was 95 %. A longer prehydrolysis time or a lower yeast inoculum size resulted in incomplete xylose conversion.

Path analysis of sex difference, forebrain commissure area and brain size in relation to degree of laterality in selectively bred mice.

Male and female mice from HI and LO lines selectively bred by Collins for strength of lateralization were tested for paw preference and then studied histologically to assess size of forebrain commissures and myelination of the corpus callosum. When compared to LO line mice, HI line mice were more strongly lateralized for paw preference and had larger brains as well as greater cross-sectional areas of the anterior commissure and corpus callosum. A substantial sex difference was found only for body size. Myelination of the corpus callosum did not differ consistently between the lines or sexes. Path analysis indicated that the line difference in the anterior commissure was a consequence of the difference in brain size, but corpus callosum size was actually smaller in the HI line than the LO line when brain size was taken into account. However, the size of the corpus callosum relative to brain size was not related to strength of paw preference, whereas brain size relative to corpus callosum size was positively correlated with strength of paw preference. These results support the hypothesis that the large difference in brain size between the Collins HI and LO lines is an important cause of the difference in strength of behavioral lateralization.

Heredity and alcohol-induced brain anomalies: effects of alcohol on anomalous prenatal development of the corpus callosum and anterior commissure in BALB/c and C57BL/6 mice.

Using two inbred strains of mice which have similar rates of alcohol metabolism, we asked whether prenatal alcohol exposure would cause greater incidence and severity of defects in the development of two forebrain fiber tracts, the corpus callosum and the anterior commissure, in mice prone to these defects (BALB/c) than in mice not prone to these defects (C57BL/6). Pregnant animals were fed 0.6 kcal/g body weight of a Sustacal-based liquid diet containing 0, 15, 17.5, 20, or 25% ethanol-derived calories from day 7 to fetal assessment on day 18 of gestation. Most of alcohol's greatest effects and the greatest strain differences in alcohol's effects on fetal variables were produced by the 17.5% diet. This dose had inhibitory effects on fetal body, brain, and midsagittal corpus callosum and anterior commissure growth. All these effects, except that on brain weight, were significantly greater in C57s than in BALBs. When the results were compared with prenatal growth curves for normal untreated mice, the effect of alcohol on corpus callosum but not anterior commissure growth was largely explained by its effects on overall development. The 17.5% diet had a greater specific effect on size of the anterior commissure in C57s than BALBs but increased the incidence and severity of its permanent dysmorphology in BALBs more than in C57s. Anterior commissure size and morphology may be sensitive indicators of alcohol's effects on prenatal brain development. Hereditary differences in rate of maternal alcohol metabolism no doubt have important consequences for risks arising from prenatal alcohol exposure. However, this study clearly indicates that inherited factors, other than those that influence rate of alcohol metabolism, are important influences on the overall fetal response and the specific responses of the anterior commissure to prenatal alcohol exposure.